Surface-enhanced Raman spectroscopy (SERS) sensors offer many advantages for chemical analyses, including the ability to provide chemical specific information and multiplexed detection capability at specific locations. However, to have operative SERS sensors for probing microenvironments, probes with high signal enhancement and reproducibility are necessary. To this end, dynamic enhancement of SERS (i.e., in-situ amplification of signal-to-noise and signal-to-background ratios) from individual probes has been explored. In this paper, we characterize the use of optical tweezers to amplify SERS signals as well as suppress background signals via trapping of individual SERS active probes. This amplification is achieved through a steady presence of a single "hot" particle in the focus of the excitation laser. In addition to increases in signal and concomitant decreases in non-SERS backgrounds, optical trapping results in an eightfold increase in the stability of the signal as well. This enhancement strategy was demonstrated using both single and multilayered SERS sub-micron probes, producing combined signal enhancements of 24-fold (beyond the native 10 SERS enhancement) for a three-layered geometry. The ability to dynamically control the enhancement offers the possibility to develop SERS-based sensors and probes with tailored sensitivities. In addition, since this trapping enhancement can be used to observe individual probes with low laser fluences, it could offer particular interest in probing the composition of microenvironments not amenable to tip-enhanced Raman spectroscopy or other scanning probe methods (e.g., intracellular analyses, etc.).
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http://dx.doi.org/10.1177/0003702816662881 | DOI Listing |
Adv Sci (Weinh)
December 2024
Department of Agriculture, Forestry and Bioresources, Seoul National University, Seoul, 08826, Republic of Korea.
Plants communicate through volatile organic compounds (VOCs), but real-time monitoring of VOCs for plant intercommunication is not practically possible yet. A nanobionic VOC sensor plant is created to study VOC-mediated plant intercommunication by incorporating surface-enhanced Raman scattering (SERS) nanosensors into a living plant. This sensor allows real-time monitoring of VOC with a sensitivity down to the parts per trillion level.
View Article and Find Full Text PDFMicrosyst Nanoeng
December 2024
Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, MO, 65211, USA.
A new high-sensitivity, low-cost, Surface Enhanced Raman Spectroscopy (SERS) sensor allows for the rapid multiplex detection of foodborne pathogens in raw poultry. Self-assembled microspheres are used to pattern a hexagonal close-packed array of nanoantennas onto a side-polished multimode fiber core. Each microsphere focuses UV radiation to a photonic nanojet within a layer of photoresist on the fiber which allows the nanoantenna geometry to be controlled.
View Article and Find Full Text PDFChem Soc Rev
December 2024
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, School of Electronic Science and Engineering, College of Environment and Ecology, State Key Laboratory of Marine Environmental Science, Department of Physics, iChEM, IKKEM, Xiamen University, Xiamen 361005, China.
Surface-enhanced Raman spectroscopy (SERS) has evolved significantly over fifty years into a powerful analytical technique. This review aims to achieve five main goals. (1) Providing a comprehensive history of SERS's discovery, its experimental and theoretical foundations, its connections to advances in nanoscience and plasmonics, and highlighting collective contributions of key pioneers.
View Article and Find Full Text PDFACS Photonics
December 2024
School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, U.K.
Tightly confined plasmons in metal nanogaps are highly sensitive to surface inhomogeneities and defects due to the nanoscale optical confinement, but tracking and monitoring their location is hard. Here, we probe a 1-D extended nanocavity using a plasmonic silver nanowire (AgNW) on mirror geometry. Morphological changes inside the nanocavity are induced locally using optical excitation and probed locally through simultaneous measurements of surface enhanced Raman scattering (SERS) and dark-field spectroscopy.
View Article and Find Full Text PDFAnal Chem
December 2024
School of Basic Medical Sciences, Zhengzhou University, Zhengzhou 450001, China.
Fibroblast activation protein (FAP) is an important antigen in the tumor microenvironment, which plays a crucial role in promoting extracellular matrix remodeling and tumor cell metastasis. A circulating form of soluble FAP has also been identified in the serum, becoming a biomarker for pan-cancer diagnosis and prognosis. However, the current peptide substrate-based enzymatic activity detection or antibody-dependent detection methods have been hindered by insufficient selectivity and complex operations, so it is valuable to develop effective nucleic acid aptamers as FAP affinity ligands.
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